Method of progressively perforating a sheet of metal



Jan. 21, 1947. R THQRP 2,414,567

METHOD OF PROGRESSIVELY PERFORATING A SHEET OF METAL Filed March 9, 1942 Patented Jan. 21, 1947 METHOD OF PROGRESSIVEIJYTPERFORAT- 'ING A'SHEET F METAL .l'oelRQThorp, West Fulton Company, :tiim of Wisconsin Allis Wis, jassignorfl to- 'T he West Allis, Wis, '21. corpora- Application March 9, 1942, Serial No. 433;.971 ZClair'ns. (o1.11a 116) 'Ihe1pre sent invention relates generally to im- ..p .fflflfimdnts in the art of producing structures jrorn sheet metal or thelike with the aid of ;;punche s and dies, and relates more specifically to an improved sheet metal rack assemblage and to an improved method of forming the same.

An...0biect.of the intention is to provide an improved hmethod of making a rack structure in firmly butremevab y supp a p u a ity of objec ts such asammllnition shells and to also :provide anflirnprovedmethod of forming such rackassemblages, i

I 'Ithas heretofore been customary in the manufacture of. niechanizedmilitary equipment, to provide amniunition racks each adapted to rejmovably, confine aselectednumber or group of loaded. shells 301i ca tridges in parallel approxi- 1113176137 horizontal position. Each of these prior shell'raclrs ordinarily consisted of a pairof laterally spaced upright end heads and a, series of horiz nta tu es o u de n r ne t t two heads, andinorderto reduce the weight pitta ad; s emb aee o ami mt wa ordinary prior practice toiforrn. each of the end heads of an aluminum casting. Because cfthe ihculty enc ountered in securing this cast metal, it been attempted to utilize sheet metal in the formation "'oi'the end" he'ads'for these shell racks, but I consider alole di fficulty has again been e countered in thesefatt'einpts, "because "these 1'- ck s man a of sturdy construction in addition -to being light 'in weight, and it required sheet II'ntal of. suchfhavy gauge with the ordinary "priorniethodsof manufacture and in order to i provide thenecessary strength, sothat' the weight of theassemblages was prohibitive.

'It is therefore "a 'iriore specific object of the 'pres'ent'invention to provide an improved mode of constructingfsheet metal shell racks of "the "general type above referred to; wherein thedesired lightness and rigiditymay be secured by utilizing relatively thin gauge sheet metal. jAnother specific object ot this invention is to provides. new and useful shell rackassemblage of compact construction adapted to snugly and safely 'confine maximum number of loaded shells or the like, while permitting rapid withdrawal cf the individual shells.

A further specific object of 'my invention is toprovide an improved durable and effective shell conf ning rackfwhich can be quickly manufactured 'frorn relativelythin sheet metal and at moderate cost, with the aid of simple punches 'anddies.

Still'ano'ther specific object ofithe invention h sh l ira pf F taken rnent, illustrating formation ofttheupper rowcf holes;

. front head fragment, showing is ,to provide a new method of forming reenforced and extremely rigid end heads for shell racks or similar structures of sheet metal or similar distortable material and with punches and dies of inexpensive construction.

, These and other specific objects andadvantages of thednvention will beapparent from the following more detailed description. i

A clear conception of the specific construction-oi one type of sheet rnetal assemblage .em-

hodying the present improvement, and of the .mode of producing the improved assemblage. a

be hadby referring to the drawing accompanying and iorming -a part of i this specification "wherein like reference charactersdesignate the ome or ar a ts in the various views, Fig. lis a front part sectional view of a typical ammunition shell rack embodying the imp v m n Fig.2 isa transverse vertical section through along the line 2-2 and showing one loaded shell inplace;

Fig. 3 is a plan View of a fragment of the sheet o m a .us d. n orm nsih r m head of the rack, depicting the initial step in the formation of this head;

K "Fig. 4 is a similar view of the same fragment -of s,he et.;meta1, showing the second step in the formation of the uppermost row of shell receiving-holes; U ,Fig. 5is another similar view of the head frag- .the thirdstep involved in the Fig. dis still another Similar view of thesame the final step involved in forming the uppermost set of holes;

flh'g. Ilsa, transverse vertical section through .thefront head, fragment of Fig. 3,;taken along .Fig. -8 is a transverse vertical section through the head fragment of Fig. 4, taken along the line Whilefthe inventionhas been shown and der scribed herein as; being applied to a particular type of ammunition shell rack formed of sheet metal, 'it is not my desire or intent to thereby unnecessarily limit the scope or restrict the utility of the improved features.

.;The. improved shell rack specifically shown in the drawing byway of of M transversely curved heads: 10,, ;-spacer-bolts is rigidly uniting the tubular flanges rugations 2|,

heads l8, so as to retain the shelves |2 in proper position; and a plurality of retractable clamps M for normally holding loaded ammunition shells l5 or the like confined within the rack, while permitting ready removal thereof.

The end heads l0, H are both formed of relatively thin gauge sheet metal, and the front head H! has a plurality of transverse rows of openings I6 therein each of which is surrounded by an integral tubular flange while the rear head II has a similargroup or number of transverse openings |8 therein of smaller diameter than the flanges i1 and openings ,rows of perforations 23 opening l6 and each of which is likewise surrounded by an integral tubular flange I9. The

corresponding sets of openings l8, l8 are disposed in horizontal axial alinement with each other; and the curved shelves |2 which serve as guides for directing the elongated loaded shells |5 into these alined openings and flanges |9, are welded or otherwise rigidlly attached to the front head It directly beneath and near the flanges l1 and penetrate arcuate slots formed in the rear head beneath the flanges l9 thereof.

Because of the light weight and other characteristics of the sheet metal used in the formation of the end heads H), II, it would be impossible to draw the relatively long tubular flanges l1, l9 out of the flat sheets from which these heads are formed, without danger of rupturing or cracking the metal, and the heads IO, M would also be insufficiently stiff or rigid if no other re-enforcing means were provided. Each end head is therefore preferably also provided with a series of transverse parallel or horizontal corrugations 2|, 22 which extend through or across the openings l8, I8 in the several rows and merge into the i9 respectively. These cor- 22 obviously reduce the extent to which the metal must be drawn or distorted at the opposite sides of the openings l6, l8 in order to form the long flanges l9, and the corrugations 2| in the front head H] are somewhat wider than the corrugations 22 in the rear head II, but both sets of corrugations 2|, 22 obviously stiffen and materially re-enforce the adjacent end heads IO, N. 7

Since the metal employed in the construction of the end heads In, II will not permit simultaneous formation of all of the corrugations 2|, 22, and also because the power required to do this would be excessive, I have evolved an improved and simple mode of forming these corrugated and punctured heads. The successive steps of this improved method are clearly depicted in Figs. 3 to 8 inclusive, and in view of the fact that the method employed in forming both heads IO, U is substantially the same, a description of the mode of producing one of these heads I'll will suffice. When forming one of the front heads In, for example, a flat sheet of metal is first provided with successive rows of laterally spaced relatively small perforations 23 as shown in Figs. 3 and 7, of which the perforations 23 in the upper row are staggered relative to those of the next lower row, and the vertical distance between the row of perforations 23 is considerably greater than the distance between successive final corrugations 2| of the completed end head ID. A die having positioning pins adapted to coact with the equally spaced small perforations 23, is next applied to the perforations of the upper row, and is manipulated to form a single corrugation 2| having local cup-shaped areas or enlargements 24 therein concentric with the perforations 23, extending along this'row' as illus- ,4 trated in Figs. 4 and 8. After the corrugation 2| has been thus formed, the center of each cupshaped area 24 is punched out to provide a larger slightly oval hole 25 therein of lesser diameter than the final opening l6, as shown in Fig. 5. An expanding punch of well known construction is thereafter forced through the row of holes 25 so as to complete the tubular flanges l1 and the openings I6 of the upper row, whereupon the same cycle of operations may be performed to complete the successive rows of corrugations 2|, l6. While the successive which ultimately locate the openings I8 are initially spaced farther apart than the horizontal center lines of the rows of corrugations 2|, these rows of perforations 23 are drawn toward each other as each new corrugation 2| is produced, and the final openings IE will be closely nested as illustrated in Figs. 1 and 2.

The spacer rods or bolts the front and rear heads In, H co-operate with the guide shelves |2 to stiffen the rack assemblage, and are preferably disposed near the outer edges of the heads so as not to interfere with other mechanism. Most of the retractable clamps I4 for normally confining the loaded shells l5 within the alined openings l6, H are formed to simultaneously co-operate with three shells l5, and the tubular flanges IQ of the rear head II are preferably tapered to fit the taper of the bullets or projectiles 2B and to prevent the shell ridges 21 from engaging the front head l0, thereby permitting the shells l5 to be readily withdrawn. The spider clamps l4 are also preferably formed of sheet metal, and each of these clamps is secured to a wire or rod 28 which is slidably and rotatably supported in both of the end heads I0, H, and the outer end of which is reversely bent to form a handle 29. Each clamp rod 28 is embraced by a compression spring 30 one end of which coacts with a sheet metal bracket 3| secured to the corresponding rod 28 near the rear head H, and the opposite end of which reacts against the inner surface of the front head In, and these springs 38 constantly urge the clamps M toward the outer front surface of the end head It]. By gripping the handle 29 and there-V after pulling and simultaneously twisting the same, the corresponding clamp M. can be retracted to release the shells |5 for free withdrawal from the openings l6, l8; and in cases where a single set of extra openings l6, I8 is available, a modified single clamp It may be utilized as shown in Fig. 1. r

The mode of constructing and of utilizing, the improved shell racks should be clearly apparent from the foregoing detailed description of the method of forming and of assembling, the same, and these racks may be of diverse sizes and. shapes and may be provided with supporting feet 32 as illustrated in Figs. 1 and 2. The improved racks are adapted to be fixedly or movably mounted in relatively cramped quarters within mobile mechanized combat units, and by virtue of their improved formation the shell racks are extremely strong and durable and may be constructed at moderate cost. The new racks may obviously be produced from'relatively light weight, inexpensive and readily available sheet metal, without sacrificing strength or rigidity, and can also be rapidly manufactured with the aid of relatively simple equipment. The various parts of each rack can be readily assembled-and rigidly united by welding or'otherwise, and the l3 which rigidly unite tion of the various invention has proven highly successful and advantageous.

It should be understood that it is not desired to limit the invention to the exact details of construction, or to the precise mode of formaparts, since various modifications within the scope of the appended claims may occur to persons skilled in the art.

I claim: 7

1. The method of progressively perforating a sheet of metal with rows of perforations each surrounded by an integral tubular flange, which comprises, forming a corrugation throughout the width of a flat sheet having a series of relatively small holes through the bottom thereof, expanding each small hole to provide larger holes each having an integral tubular flange projecting from the bottom of the corrugation, and repeating said operations to provide successive corrugations and flanged holes while gradually di- 20 minishing the plane length of the sheet transversely of the corrugations.

2. The method of progressively perforating a sheet of metal with rows of perforations each surrounded by an integral tubular flange, which comprises, providing a flat sheet with a rectilinear row of relatively small laterally spaced perforations, forming a continuous corrugation throughout the width of the sheet and having the row of perforations extending along the bottom thereof, expanding each small hole to provide larger holes each having an integral tubular flange projecting from the bottom of the corrugation, and repeating said operations to provide successive parallel corrugations and flanged holes while gradually diminishing the plane length of the sheet transversely of the corrugations.

JOEL R. THORP. 

